There is an X-ray CT scanner in which an X-ray source and a two-dimensional X-ray detector are installed in such a manner that they are opposed to each other, and X-ray imaging is performed while a pair of the X-ray source and the detector rotates around the subject. In the X-ray CT scanner, a series of measured images acquired through the detector are subjected to an arithmetic processing for reconstruction, whereby a reconstructed image is obtained, resulting in a desired cross-sectional image. The X-ray CT scanner needs measured images that are acquired by rotating the X-ray source by 180 degrees or more, in order to obtain a reconstructed image with a high degree of precision. Therefore, it is necessary to establish a large-scale apparatus.
In comparison to the X-ray CT scanner, there are small-sized devices, such as an X-ray imaging apparatus in which the X-ray source and the detector are allowed to perform rotational transfer within only a range much narrower than 180 degrees as a rotation angle, and another X-ray imaging apparatus in which the movement of the X-ray source and the detector is not the rotational transfer. As a representative example, there is a tomographic apparatus that linearly moves the X-ray source and the detector respectively in the directions opposite to each other, so as to perform tomosynthesis imaging (e.g., see the Non Patent Document 1). The tomosynthesis imaging employs a so-called summation method that applies a summation process to the measured images obtained by the detector, so as to acquire an image.